1. Field of the Invention
The present invention generally relates to a belt-tensioning or a chain-tensioning device designed to ensure a suitable tension of a belt or chain. In particular, embodiments relate to systems and methods for ensuring a suitable tension of a belt or chain in a tension device in an automotive vehicle.
2. Brief Description of the Related Art
A tensioning device generally comprises a fixed bracket and a moving part, in the form of a cam or a swivel arm, mounted with rotational capability on the fixed bracket. A pulley is mounted in idle arrangement on the moving part by means of a rolling bearing and is intended to be brought into contact with the belt. A spring exerts a tension force between the bracket and the moving part, causing the pulley to make contact with the belt with a suitable belt tension. The moving part is mounted with adjustment capability on the bracket so as to be able to adjust the tension force of the belt, as described in FR 2 624 577 and FR 2 744 506, which describe tensioning devices.
A belt-tensioning device has to be adjusted in order to maintain the tension of the belt within a certain tolerance range. Wear of the belt or the dimensional variations of the belt caused, for example, by temperature variations, may also require device adjustments to maintain tension. The tension applied in the belt by the tensioning device is adjusted in an assembly stage with the aid of visual reference marks. The tension of the belt is checked in the course of maintenance operations.
The failure of a belt or of a tensioning device, can cause a stoppage or failure of a mechanical device connected to the belt and can impair the operating reliability of a mechanical device. A failure of a timing belt of a heat engine of an automotive vehicle can instantaneously cause serious damage to said engine.
Tensioning devices of the type described above do not prevent failure of the belt or of the tensioning device. The imminence of a belt or tensioning device failure is difficult to predict and can happen suddenly and unexpectedly.